US Patent 5674996: Cell cycle checkpoint genes

Human checkpoint huCDC34, huRAD9compA, and huRAD9compB cDNAs shown in SEQ ID Nos:7-9. A method for isolating a human checkpoint cDNA that is capable of restoring growth at a restrictive temperature in a yeast test cell, wherein the yeast test cell comprises a genome having a first gene that forms a DNA strand break at a restrictive temperature and a second gene that fails to induce a cell cycle arrest in response to the DNA strand break, whereby the growth of the yeast test cell is inhibited at the restrictive temperature, the method comprising the steps of: obtaining a human cDNA library comprising a plurality of human cDNA clones; inserting the human cDNA clones individually into plasmid vectors comprising a selectable marker gene; transforming a culture of the yeast test cells with the plasmid vectors from the preceding step; selecting for yeast test cells transformed with the selectable marker gene; growing the selected transformants at the restrictive temperature and isolating a candidate transformant capable of growing at the restrictive temperature; and identifying the human cDNA carried by the candidate transformant as a human checkpoint cDNA by sequencing the human cDNA carried by the candidate transformant and determining that the human cDNA is less than 50% homologous with both the first gene and the second gene. Also yeast checkpoint RAD17, RAD24, MEC1, MEC2, and MEC3 cDNAs shown in SEQ ID Nos:10-19.